miR-219-1-3p is a negative regulator of the mucin MUC4 expression and is a tumor suppressor in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal cancers in the world with one of the worst outcome. The oncogenic mucin MUC4 has been identified as an actor of pancreatic carcinogenesis as it is involved in many processes regulating pancreatic cancer cell biology. MUC4 is not expressed in healthy pancreas whereas it is expressed very early in pancreatic carcinogenesis. Targeting MUC4 in these early steps may thus appear as a promising strategy to slow-down pancreatic tumorigenesis. miRNA negative regulation of MUC4 could be one mechanism to efficiently downregulate MUC4 gene expression in early pancreatic neoplastic lesions. Using in silico studies, we found two putative binding sites for miR-219-1-3p in the 3'-UTR of MUC4 and showed that miR-219-1-3p expression is downregulated both in PDAC-derived cell lines and human PDAC tissues compared with their normal counterparts. We then showed that miR-219-1-3p negatively regulates MUC4 mucin expression via its direct binding to MUC4 3'-UTR. MiR-219-1-3p overexpression (transient and stable) in pancreatic cancer cell lines induced a decrease of cell proliferation associated with a decrease of cyclin D1 and a decrease of Akt and Erk pathway activation. MiR-219-1-3p overexpression also decreased cell migration. Furthermore, miR-219-1-3p expression was found to be conversely correlated with Muc4 expression in early pancreatic intraepithelial neoplasia lesions of Pdx1-Cre;LSL-Kras(G12D) mice. Most interestingly, in vivo studies showed that miR-219-1-3p injection in xenografted pancreatic tumors in mice decreased both tumor growth and MUC4 mucin expression. Altogether, these results identify miR-219-1-3p as a new negative regulator of MUC4 oncomucin that possesses tumor-suppressor activity in PDAC.

Decreased beta-cell proliferation impairs the adaptation to pregnancy in rats malnourished during perinatal life.

We investigated the cellular mechanisms responsible for the inability of 8-month-old previously malnourished (PM) females to adapt their beta-cell mass during pregnancy. The evolution during pregnancy of beta-cell fraction, size and proliferation was studied. At day 21 of pregnancy beta-cell fraction increased less in PM than in control females, compared with their non-pregnant values. A slight beta-cell hypertrophy was observed during pregnancy in both groups. In control females, beta-cell 5-bromo-2'-deoxyuridine (BrdU) labelling index (LI) increased from 0.07+/-0.04% before pregnancy to 1.13+/-0.20% at day 12 and decreased thereafter to reach again basal levels at day 21. In PM females, beta-cell proliferation rate was decreased at day 12 (0.74+/-0.15%, P<0.05) but similar to controls at all other stages studied. Separate analysis of the head and tail parts of the pancreas in control animals revealed that the beta-cell fraction during pregnancy increased more in the head than in the tail; similarly, BrdU LI increased 20-fold in the head and 10-fold in the tail, compared with non-pregnant values. In PM females, no adaptation of beta-cell fraction could be observed in the head, where BrdU LI was decreased by half at day 12 of pregnancy. In PM females the lactogenic activity was twice that of controls at day 12 whereas all beta-cells expressed the prolactin receptor. In conclusion, perinatal malnutrition impairs subsequent adaptation to pregnancy by decreasing beta-cell proliferation in the head of the pancreas at a critical time during pregnancy.

Experimental investigation of a diffraction tomography technique in fluid ultrasonics.

Qualitative ultrasonic imaging of cylindrical fluid targets is investigated by a diffraction tomography technique applied to experimental data. The principles of the image formulation are stated and an experimental setup is described. Experimental difficulties related to the short wavelength used and respective advantages in collecting the data, either with a mechanically scanned single transducer or with an electronically scanned array of transducers, are emphasized. Representative images of simply structured phantoms and of real biological bodies are obtained in spite of the small number of views available.

[Hepatocellular carcinoma in cirrhosis: semeiology and performance of magnetic resonance imaging and lipiodol computed tomography]. / Carcinome hépatocellulaire sur cirrhose: sémiologie et performances de l'imagerie par résonance magnétique et de la tomodensitométrie après artériographie lipiodolée.

OBJECTIVES: a) Describe hepatocellular semiology in magnetic resonance imaging and lipiodol computerized tomography in patients with cirrhosis, who are candidates for surgery; b) Clarify the respective roles of magnetic resonance imaging and lipiodol computerized tomography in hepatocellular detection. METHODS: Twenty four patients with suspected hepatocellular carcinoma underwent successive magnetic resonance imaging and lipiodol computerized tomography. Thirty-four of the 67 lesions seen by lipiodol computerized tomography and 28 of 52 lesions seen by magnetic resonance imaging were confirmed histologically. RESULTS: In lipiodol computerized tomography, 44% of hepatocellular carcinomas had a dense and homogeneous pattern; 24% had a homogeneous but slightly dense pattern. Sixteen distinct deposits were described: 4 were confirmed as hepatocellular carcinoma and 12 were not controlled histologically. In magnetic resonance imaging 57% of hepatocellular carcinomas have a high intensity on T1 and T2 weighted spin echo images, 38% were hyperintense on T2 and hypo or isointense on T1 weighted images. Eighty-six percent of hyperintense T1 and T2 weighted images were hepatocellular carcinoma. When the gold standard was histology, lipiodol computerized tomography sensitivity (81%) was higher than magnetic resonance imaging (68%). When the gold standard was lipiodol computerized tomography, the sensitivity of magnetic resonance imaging was 47 +/- 12%. CONCLUSIONS: a) The sensitivity of lipiodol computerized tomography was better than resonance magnetic imaging; b) the homogeneous and slightly dense pattern corresponded to a hepatocellular carcinoma in 50% of cases; c) on magnetic resonance imaging any lesions with high intensity on T1 and T2 spin echo images strongly suggests hepatocellular carcinoma; d) if surgical resection after ultrasonography is being considered, the second step should be an magnetic resonance imaging.

The MUC4 mucin mediates gemcitabine resistance of human pancreatic cancer cells via the Concentrative Nucleoside Transporter family.

The fluorinated analog of deoxycytidine, Gemcitabine (Gemzar), is the main chemotherapeutic drug in pancreatic cancer, but survival remains weak mainly because of the high resistance of tumors to the drug. Recent works have shown that the mucin MUC4 may confer an advantage to pancreatic tumor cells by modifying their susceptibility to drugs. However, the cellular mechanism(s) responsible for this MUC4-mediated resistance is unknown. The aim of this work was to identify the cellular mechanisms responsible for gemcitabine resistance linked to MUC4 expression. CAPAN-2 and CAPAN-1 adenocarcinomatous pancreatic cancer (PC) cell lines were used to establish stable MUC4-deficient clones (MUC4-KD) by shRNA interference. Measurement of the IC50 index using tetrazolium salt test indicated that MUC4-deficient cells were more sensitive to gemcitabine. This was correlated with increased Bax/BclXL ratio and apoptotic cell number. Expression of Equilibrative/Concentrative Nucleoside Transporter (hENT1, hCNT1/3), deoxycytidine kinase (dCK), ribonucleotide reductase (RRM1/2) and Multidrug-Resistance Protein (MRP3/4/5) was evaluated by quantitative RT-PCR (qRT-PCR) and western blotting. Alteration of MRP3, MRP4, hCNT1 and hCNT3 expression was observed in MUC4-KD cells, but only hCNT1 alteration was correlated to MUC4 expression and sensitivity to gemcitabine. Decreased activation of MAPK, JNK and NF-κB pathways was observed in MUC4-deficient cells, in which the NF-κB pathway was found to have an important role in both sensitivity to gemcitabine and hCNT1 regulation. Finally, and in accordance with our in vitro data, we found that MUC4 expression was conversely correlated to that of hCNT1 in tissues from patients with pancreatic adenocarcinoma. This work describes a new mechanism of PC cell resistance to gemcitabine, in which the MUC4 mucin negatively regulates the hCNT1 transporter expression via the NF-κB pathway. Altogether, these data point out to MUC4 and hCNT1 as potential targets to ameliorate the response of pancreatic tumors to gemcitabine treatment.

Glucocorticoid signalling affects pancreatic development through both direct and indirect effects.

AIMS/HYPOTHESIS: Beta cell development is sensitive to glucocorticoid levels. Although direct effects of glucocorticoids on pancreatic precursors have been shown to control beta cell mass expansion, indirect effects of these hormones on pancreatic development remain unexplored. This issue was addressed in mice lacking the glucocorticoid receptor (GR) in the whole organism. MATERIALS AND METHODS: The pancreatic phenotype of GR(null/null) mice was studied at fetal ages (embryonic day [E]) E15.5 and E18 by immunohistochemistry and beta cell fraction measurements. To distinguish between direct and indirect effects, mutant E15.5 fetal pancreata were grafted under the kidney capsule of immunodeficient mice and analysed after 1 week. RESULTS: E18 GR(null/null) fetuses had smaller digestive tracts and tiny pancreata. Massive pancreatic disorganisation and apoptosis were observed despite the presence of all cell types. E15.5 GR(null/null) mutants were indistinguishable from wild-type regarding pancreatic size, tissue structure and organisation, beta cell fraction and production of exocrine transcription factor Ptf1a, neurogenin 3 and Pdx-1. Grafting E15.5 GR(null/null) pancreata into a GR-expressing environment rescued the increased apoptosis and mature islets were observed, suggesting that GR(null/null) pancreatic cell death can be attributed to indirect effects of glucocorticoids on this tissue. Heterozygous GR(+/null) mutants with reduced GR numbers showed no apoptosis but increased beta cell fraction at E18 and the adult age, strengthening the importance of an accurate GR dosage on beta cell mass expansion. CONCLUSIONS/INTERPRETATION: Our results provide evidence for GR involvement in pancreatic tissue organisation and survival through indirect effects. GR does not appear necessary for early phases, but its accurate dosage is critical to modulate beta cell mass expansion at later fetal stages, presumably through direct effects.

Endocrine pancreas development is altered in foetuses from rats previously showing intra-uterine growth retardation in response to malnutrition.

AIMS/HYPOTHESIS: We have shown that perinatal malnutrition decreases beta-cell mass at birth and impairs the adaptation of the endocrine pancreas to a subsequent pregnancy. The aim of this study is to investigate the impact of this maternal inadaptation on the development of endocrine pancreas in foetuses. METHODS: Female rats malnourished during their perinatal life and showing intra-uterine growth retardation at birth were mated at 8 months of age. The development of the endocrine pancreas was studied at embryonic days 14, 17 and 20 in their foetuses by immunohistochemistry and morphometrical measurements on pancreatic sections. RESULTS: At embryonic day 20, both alpha and beta-cell fractions were decreased in foetuses from IUGR dams. Beta-cell mass was reduced (197 +/- 27 microg, vs 281 +/- 40 microg in control, p < 0.01) and so were insulin content and islet number per cm(2), as in the first generation foetuses. At embryonic day 14, the number of cells expressing only insulin was decreased by half in foetuses from intra-uterine growth retardation dams. At embryonic day 17, 50 % of the homeodomain protein Pdx-1 cell population expressed insulin but all the insulin cells expressed Pdx-1 in both groups; in foetuses from intra-uterine growth retardation dams the number of epithelial cells expressing Pdx-1 was decreased (415 +/- 40 cells/ mm(2) vs 481 +/- 28 cells/mm(2) in control foetuses, p < 0.05) and the mesenchymal fraction in the pancreas was increased by 36 % ( p < 0.05). CONCLUSION/INTERPRETATION: Early malnutrition decreases beta-cell mass in the first generation of offspring and impairs the subsequent beta-cell adaptation to pregnancy. The beta-cell alteration is also present in the next generation and involves a decreased expansion of the epithelial population expressing Pdx-1.

Localization of alpha-endosulphine in pancreatic somatostatin delta cells and expression during rat pancreas development.

AIMS/HYPOTHESIS: alpha-Endosulphine, a protein that belongs to the cAMP-regulated-phosphoprotein family, has been reported to modulate insulin secretion in vitro through interaction with the pancreatic beta-cell ATP-sensitive potassium (K(ATP)) channel. In this study, we analysed the tissue distribution of alpha-endosulphine and determined its pancreatic cellular localization. METHODS: Quantitative tissue distribution of alpha-endosulphine was studied by RIA on tissue extracts and cellular/subcellular localization was done using immunocytochemistry, morphometry and western blot analysis. alpha-Endosulphine and somatostatin release from RINT-3 somatostatin-secreting cells was quantified by RIA. RESULTS: alpha-Endosulphine, concentrated particularly in the central nervous system, was also detected in a wide variety of tissues including the pancreas. Immunohistochemistry analysis of adult rat pancreatic sections showed that alpha-endosulphine localized in somatostatin delta cells, where its expression increased during post-natal development. Immunoreactive cells were detected from foetal age E19, and the number of somatostatin cells co-expressing alpha-endosulphine increased with developmental age from E19 until adult. alpha-Endosulphine, highly expressed in the cytoplasm of RINT3 somatostatin-secreting cell line, was recovered in the particulate fraction of RINT3 cell extracts but was not co-secreted with somatostatin. CONCLUSION/INTERPRETATION: alpha-Endosulphine is expressed in all tissues tested including pancreas and is also detected in plasma. Pancreatic alpha-endosulphine is specifically localized in somatostatin delta cells. This cytosolic protein is not co-secreted with somatostatin and could be physically associated with particulate components of the cells. These findings are not in favour of an endocrine/paracrine effect of alpha-endosulphine on the beta-cell K(ATP) channel.